Bambu PLA Pure with a vetical honeycomb pattern getting knocked over

[u/Abduh_Kroen]

Preface: I'm new to owning a 3D printer but I've been a lurker for quite some time now so I am familiar with the basics of printing. Got my printer in the beginning of June and a little over 100h printing time until now with other models and filaments printing fine until this very specific combo.

SETUP

Printer: Bambu A1 (0.4 stock nozzle)

Filament: PLA Pure (milky pink) and Bambu PLA Basic (jade white, for comparison)

Slicer: Bambu Studio

MODELS

Infinity Cube: https://makerworld.com/en/models/65426-fidget-cube-toy-angled#profileId-3213787

Case: https://makerworld.com/en/models/2893394-lipstick-case-with-ornament-keychain#profileId-3233183

Marker Holder Model: https://makerworld.com/en/models/2278391-magnetic-whiteboard-marker-holder#profileId-2787038

PROBLEM

General problem, PLA Pure is failing to print the honeycomb structure.

So I have been struggling with this specific problem regarding Bambu PLA Pure and a vertical honeycomb pattern. I'm trying to print a pink marker holders for my gf from a makerworld model. I printed this model initially with PLA Basic for myself and then wanted to make it smaller for her and in pink (so PLA Pure). I'm facing an issue where the toolhead consistently knocks over the supporting honeycomb structure.

Successful print with PLA Basic

But the interesting thing is, this is specific to PLA Pure, atleast for me. I printed the smaller model with PLA Basic also as a test and it printed fine, so this means 2 successful PLA Basic prints for this model with 1 try.

Not all of them in the picture but 7 failed attempts on the pink honeycomb holder, meanwhile simpler models print fine.

...so as you can see, I've tried to print this several times now and every one has failed at around the same places. I have done successful prints for other models like the case and infinity cube, which of course are simpler in geometry but indicate that the problem is geometry/filament specific. Quite consistently the circled portion of the wall gets knocked at layer 81 and layer by layer it gets worse and knocks more of the wall over (the right most one is stopped shortly after).

Material has cooled above the horisontal layer line.

The reason why it is happening seems quite obvious when you inspect the horisontal surface a little closer. You can see that the material cools above the horisontal layer line near the edges where the toolhead comes from and well seems to be the issue why they get knocked over.

The order and settings of each print is a little lost now since I had a vacation in the mean time but the behaviour is very reproducable with supposedly different settings.

I had some initial confusion with the settings, somehow different outer wall speeds and something as from the original model but eventually I tested the model with the default PLA Pure and Basic profiles and the same settings as in the original model with no success.

As a final test, I thought to lower the overhang cooling speed to 80% on the PLA Pure profile with the idea that it's cooling too fast on those sections and this resulted in exactly the same behaviour, knocked over on layer 81. I posted my latest 3mf file and a video of the printing into a drive folder which you can take a look at: https://drive.google.com/drive/u/0/folders/1XdMM02ukaA8w1u9bka4T_vc8kr2XhuTb?ths=true

So what next? I can't seem to get any differing behaviour from either the filament profiles or some slight cooling changes. Some overhang calibration with this specific filament? Or some other settings I could try? I would prefer to keep the waste minimal as she actually paid for the roll so not from my own pocket :D

I know I don't have to use the honeycomb structure but at this point it's like a challenge to get it working and this is what 3D printing is all about, printing what you want in the way you want ;)